Chemokine expression during acute rejection of rat kidneys

During acute rejection of fully allogeneic rat renal allografts, few neutro phil granulocytes are detected, whereas an abundant infiltrate of macrophag es and T lymphocytes becomes apparent. The mechanisms leading to this speci fic pattern of infiltration are not understood. We performed a sequential d aily Northern blot analysis of the mRNA expression of the CC-chemokines MCP -1, MIP-1 alpha and RANTES and of the CXC-chemokines GRO/KC and MIP-2 in ra t renal isografts (LEW --> LEW, n = 1 per day) and allografts during acute rejection (DA --> LEW, n = 3 per day). MCP-1 gene expression strongly incre ased on days 3-4 after allotransplantation and returned to control levels o n day 6. The expression of MIP-1 alpha and RANTES continuously rose until d ay 3-4 and remained stable thereafter. Isografts displayed minor changes in CC-chemokine expression. In contrast to CC-chemokines, GRO/KC was expresse d in low amounts during rejection and MIP-2 mRNA remained undetectable. In conclusion, the expression of the CC-chemokines MCP-1, MIP-1 and RANTES was clearly upregulated during rejection, whereas the mRNA of the CXC-chemokin es MIP-2 and GRO/KC was not detected at all or remained at low levels. This pattern of chemokine gene expression is in good accordance with the predom inant mononuclear leukocyte infiltrate in allografts.